The present invention relates to a technique for manufacturing a resin-sealed type semiconductor device using a lead frame and more particularly to a technique effective in its application to the manufacture of a semiconductor device (a non-leaded type semiconductor device) in which external electrode terminals are exposed to mounting side faces without intentional projection sideways of a package, such as SON (Small Outline Non-Leaded Package) and QFN (Quad Flat Non-Leaded Package).
In the manufacture of a resin-sealed type semiconductor device there is used a lead frame. The lead frame is fabricated by forming a metallic plate into a desired pattern by blanking with a precision press or by etching. The lead frame has a tab for fixing a semiconductor element (semiconductor chip), a support portion called die pad, and plural leads whose front ends (inner ends) face an outer periphery of the support portion. The tab is supported by tab suspension leads extending from a frame portion of the lead frame.
In manufacturing a resin-sealed semiconductor device with use of such a lead frame, a semiconductor chip is fixed to the tab of the lead frame, electrodes on the semiconductor chip and the front ends, or the inner ends, of the leads are connected together using conductive wires, then the inner end sides of the leads, including the wires and the semiconductor chip, are sealed with an insulating resin to form a seal member (package), thereafter, an unnecessary lead frame portion is cut off and at the same time lead portions and tab suspension lead portions projecting from the package are cut off.
On the other hand, as one of resin-sealed type semiconductor devices manufactured using a lead frame there is known a semiconductor device (non-leaded type semiconductor device) wherein a package is formed by one-side molding on one side of a lead frame and leads as external electrode terminals are exposed to one side of the package, without intentional projection of the leads from a peripheral surface of the package. As this type of semiconductor devices there are-known an SON wherein leads are exposed to both side edges of one surface of a package and a QFN wherein leads are exposed to four sides of one surface of a quadrangular package.
As an example of a bleeding preventing technique there is known a technique disclosed in Japanese Published Unexamined Patent Application No. Hei 11 (1999)-345897. In this unexamined publication is disclosed Fan-out-BGA of a structure having been subjected to processing for the prevention of bleeding of Ag paste, such as the formation of a solder resist dam or blasting (abrasive polishing).
On the other hand, in Japanese Published Unexamined Patent Application No. 2000-196006 is disclosed a QFP (Quad Flat Package) type semiconductor device of a structure wherein lugs projecting toward the interior of a sealing resin are formed on side faces of a die pad for the purpose of improving a close adherence between the die pad and the sealing resin and also improving moisture resistance. According to the structure of this semiconductor device, the back side of the die pad is exposed from the sealing resin.
Further, in Japanese Published Unexamined Patent Application No. Hei 11 (1999)-251494 is disclosed a high-frequency device having a gull wing type wire structure for use in a portable telephone or the like in which a semiconductor element mounting portion serves as ground. According to the technique disclosed therein, not only electrodes on a semiconductor element and the leads are connected together through wires, but also the electrodes on the semiconductor element and the semiconductor element mounting portion are connected together through wires because of a die pad serving as ground. This is called down bonding in the literature just referred to above. Because of down bonding, the semiconductor element mounting portion is larger than the semiconductor element, and in a mounted state of the semiconductor device the semiconductor element mounting portion projects to the outside of the semiconductor device.